1. Field of the Invention
The present invention relates to an antenna device, and more particularly to an antenna device applied to a wireless communication product.
2. The Related Art
Nowadays, people are in an era of wireless communication technology being used everywhere, for example, talking on cell phones, information transmission and global positioning system navigation must rely on the wireless communication technology to be completed. As is known to all, in wireless communication system which is based on the wireless communication technology, an antenna device applied to a wireless communication product is often used as a carrier for receiving and sending electromagnetic wave signals. When the antenna device sends the electromagnetic wave signals, electric currents are converted into the electromagnetic wave signals. When the antenna device receives the electromagnetic wave signals, the electromagnetic wave signals are converted into the electric currents. Wireless communications include long distance wireless communications and short distance wireless communications. In the short distance high-frequency wireless communication, because a dimension of the antenna device is inversely proportional to a frequency of the electromagnetic wave signal, the dimension of the antenna device should be decreased for receiving and sending the high-frequency electromagnetic wave signals. In addition, in the short distance high-frequency wireless communication, the antenna device presents a high directivity characteristic in the process of receiving and sending the electromagnetic wave signals that makes radiation energies of the antenna device concentrated.
However, in spite of the dimension of the antenna device being decreased, receiving and sending frequencies of the antenna device are unable to reach a frequency band requirement of the high-frequency wireless communication. Moreover, in the short distance high-frequency wireless communication, the antenna device presents the high directivity characteristic in the process of receiving and sending the electromagnetic wave signals that makes the radiation energies of the antenna device concentrated. As a result, wireless communication angles of the antenna device are limited.